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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2e8baa20a45cd69c38254a2ec5036aa3f7250f97bed93f9ba6bad3c4d23548c' 
  AND token = '2m4X34OGHN3rcUEwqd8B+LnacI7EY9HmyJhzhFTe/Y4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}